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Contains class and interfaces for supporting SASL.

This package defines classes and interfaces for SASL mechanisms.
It is used by developers to add authentication support for 
connection-based protocols that use SASL. 

<h4>SASL Overview</h4>
<p>

Simple Authentication and Security Layer (SASL) specifies a
challenge-response protocol in which data is exchanged between the
client and the server for the purposes of
authentication and (optional) establishment of a security layer on
which to carry on subsequent communications.  It is used with
connection-based protocols such as LDAPv3 or IMAPv4.  SASL is
described in
<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>.

<p>
There are various <em>mechanisms</em> defined for SASL.
Each mechanism defines the data that must be exchanged between the
client and server in order for the authentication to succeed.
This data exchange required for a particular mechanism is referred to
to as its <em>protocol profile</em>.
The following are some examples of mechanims that have been defined by 
the Internet standards community.
<ul>
<li>DIGEST-MD5 (<A HREF="http://www.ietf.org/rfc/rfc2831.txt">RFC 2831</a>).
This mechanism defines how HTTP Digest Authentication can be used as a SASL
mechanism.
<li>Anonymous (<A HREF="http://www.ietf.org/rfc/rfc2245.txt">RFC 2245</a>).
This mechamism is anonymous authentication in which no credentials are
necessary.
<li>External (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>).
This mechanism obtains authentication information 
from an external source (such as TLS or IPsec).
<li>S/Key (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>).
This mechanism uses the MD4 digest algorithm to exchange data based on
a shared secret.
<li>GSSAPI (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>).
This mechanism uses the 
<A HREF="http://www.ietf.org/rfc/rfc2078.txt">GSSAPI</A>
for obtaining authentication information.
</ul>

<p>
Some of these mechanisms provide both authentication and establishment
of a security layer, others only authentication.  Anonymous and
S/Key do not provide for any security layers.  GSSAPI and DIGEST-MD5
allow negotiation of the security layer.  For External, the
security layer is determined by the external protocol.

<h4>Usage</h4>

<p>
Users of this API are typically developers who produce
client library implementations for connection-based protocols,
such as LDAPv3 and IMAPv4,
and developers who write servers (such as LDAP servers and IMAP servers).
Developers who write client libraries use the
<tt>SaslClient</tt> and <tt>SaslClientFactory</tt> interfaces.
Developers who write servers use the
<tt>SaslServer</tt> and <tt>SaslServerFactory</tt> interfaces.
<p>
Among these two groups of users, each can be further divided into two groups:
those who <em>produce</em> the SASL mechanisms and those 
who <em>use</em> the SASL mechanisms.
The producers of SASL mechanisms need to provide implementations
for these interfaces, while users of the SASL mechanisms use 
the APIs in this package to access those implementations.

<h2>Related Documentation</h2>

Please refer to the 
<a href="../../../../technotes/guides/security/sasl/sasl-refguide.html">Java 
SASL Programming Guide</a> for information on how to use this API.


@since 1.5


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